#使用列表
numbers = [7, -7, 2, 3, 2]
print(numbers)
print(numbers+numbers)
print(numbers*2)
lst = [3, (1,), 'dog', 'cat']
print(lst[0])
print(lst[1])
print(lst[2])
print(lst[1:3])
print(lst[2:])
print(lst[-3:])
print(lst[:-3])
for i in range(len(lst)):  # 通历列表lst
    print(lst[i], end=" ")


